The present invention relates to pool cleaning robots. More particularly it relates to apparatus and method for cleaning the bottom of a pool.
There are many types of automatic pool cleaners available, exhibiting various navigational abilities and ways of cleaning the bottom of a pool.
For example, in U.S. Pat. No. 6,125,492 (Prowse), titled Automatic Swimming Pool Cleaning Device, there was disclosed an automatic swimming pool cleaning device, which includes a flexible cleaning member designed to contact an underwater surface of the swimming pool. A tube is coupled to the cleaning member for connecting the cleaning device to a water vacuum hose via hose adaptor. Water and pool surface contamination is drawn from underneath the cleaning member up through the tube by suction to a water filter system before being returned to the pool. A flexible valve member is mounted proximate a throat region of the tube wherein as water is drawn up through the tube a decrease in pressure in the throat region causes the valve member to flex and momentarily interrupt the flow of water. The interruption to the flow of water through the tube results in a momentary differential of ambient pressure underneath the flexible cleaning member which enables the device to move forwards incrementally along the underwater surface of the pool.
U.S. Pat. No. 6,099,658 (Porat), titled Apparatus and Method of Operation for High-Speed Swimming Pool Cleaner disclosed an apparatus and method for cleaning the bottom and vertical side walls of a swimming pool, pond or tank employing a robotic, self-propelled cleaner. The robot has a protective housing of conventional design, the cleaner being operated at a primary cleaning speed as it traverses the surfaces to be cleaned and until the cleaner housing emerges from the water along a sidewall of the pool; thereafter the cleaner operates at a secondary drive speed that is relatively slower than the primary speed and the cleaner thereafter reverses direction and descends for a pre-determined period of time at the slower secondary speed in order to permit the air entrained under the housing to escape without destabilizing the cleaner during descent. After the predetermined period of time, the cleaner resumes operation at the more rapid primary speed until the cleaner housing once again emerges from the water""s surface, after which the cycle is repeated.
In U.S. Pat. No. 5,086,535 (Grossmeyer et al.) titled Machine and Method Using Graphic Data for Treating A Surface, there was disclosed a machine for treating a surface area within a boundary perimeter includes a self propelled chassis having a surface treating device mounted on it. A computing section is mounted on the chassis and a powered wheel (or each of plural powered wheels) has a motor module for receiving command signals from the computing section. A position sensor is coupled to the computing section for generating a feedback signal representing the actual position of the machine. A data loading device coacts with the computing section for transmitting data to such computing section. A data file stores graphic data developed from a graphic depiction representing the surface area to be treated as well as other data developed in other ways. The data file coacts with the computing section and transmits graphic and other data to it. The computing section is arranged for processing the data and the feedback signal and responsively generating command signals directed to each motor module. Such modules, and the motors controlled thereby, propel the machine over the surface area selected to be treated.
U.S. Pat. No. 5,569,371 (Perling) titled System For Underwater Navigation and Control of Mobile Swimming Pool Filter, disclosed an underwater navigation and control system for a swimming pool cleaning robot, having a driver, an impeller, a filter and a processor for controlling the driver and a signal-producing circuit. The system further includes a signal-detecting circuit mounted on the pool, an interface located on the ground in proximity to the pool and comprising a detector for receiving and processing data from the detecting circuit and for transmitting signals to the robot""s processor. Determination of the actual robot location is performed by triangulation in which the stationary triangulation base is defined by at least two spaced-apart signal detectors and the mobile triangle apex is constituted by the signal-producing circuit carried by the robot.
U.S. Pat. No. 5,197,158 (Moini) titled Swimming Pool Cleaner, disclosed a vacuum powered automatic swimming pool cleaning device having a hollow housing supported on two pairs of device mover wheels. The housing includes a central water suction chamber in water flow communication with a water suction trough at the bottom of the housing and in water outlet communication with an external vacuum line, a gear train for driving one of the pairs of mover wheels, and pivoted directional control floats. The water suction chamber houses an axle mounted turbine wheel bearing water driven vanes with the turbine being rotated in one direction only by water flow through the chamber. The turbine axle bears a turbine power output drive gear which intermeshes with one or the other of two shift gears which in turn reversibly drive the gear train as dictated by the position of the directional control floats within the housing. The floats swing shift within the housing to shift the shift gears in response to the impact of the cleaning device on an obstruction on the pool floor or by the device impacting a vertical pool wall. The swing shift of the control floats reverses the rotation of the mover wheels and thus the direction of movement of the cleaning device on the pool floor.
U.S. Pat. No. 4,786,334 (Nystrom) titled Method of Cleaning the Bottom of a Pool, disclosed a method of cleaning the bottom of a pool with the aid of a pool cleaner. The pool cleaner travels along the bottom of the pool and collects material lying at the bottom of the pool. The pool cleaner is arranged to travel to and fro in straight, parallel paths between two opposite walls of the pool. At the walls the pool cleaner is turned by rotating a half turn so that, after turning, it will have been displaced laterally perpendicular to the initial direction of travel.
In U.S. Pat. No. 4,593,239 (Yamamoto) titled Method and Apparatus for Controlling Travel of an Automatic Guided Vehicle, there was disclosed an automatic guided vehicle detects marks located on a plurality of points along a route it travels using at least three sensors, selects the number of marks detected from each individual sensor as a reference value in accordance with the logic of majority, and stops when the reference value agrees with a predetermined value. Cumulative errors, caused by misdetection are thus avoided and, there is little cumulative error.
U.S. Pat. No. 4,700,427 (Kneppers), titled Method of Automatically Steering Self-Propelled Floor-Cleaning Machines and Floor-Cleaning Machine for Practicing the Method, disclosed a method of automatically steering a self-propelled floor-cleaning machine along a predetermined path of motion on a limited area to be worked. A sequence of path segments stored in a data memory is retrieved, and the path segments travelled by the machine. Markings are recognized by at least one sensor and converted into course-correcting control commands actuating and/or steering the machine.
U.S. Pat. No. 3,979,788 (Strausak) titled mobile machine for cleaning swimming pools, disclosed a Mobile Machine for Cleaning Swimming Pools by suction removal of sediment from the bottom of the swimming pools comprises a water turbine driving a drive wheel in such a way that the machine follows a self-steered path on the bottom of the swimming pools. The drive wheel is capable of rotating about a vertical steering axle to prevent the machine from becoming blocked at a wall or in a corner of the swimming pools.
It is noted that covering efficiently and quickly the bottom (and side walls) of a swimming pool is not simple a task, and various scanning algorithms (see some of the above-mentioned patents for examples) were devised to try and overcome this complex problem. Contributing to the complexity of the navigational problem is the fact that even though a robot is generally programmed to travel in straight lines from side to side and take accurate turns, it is difficult to keep it on such path and turns are hard to direct accurately. In fact a travel pattern of a pool cleaning robot is more likely to be deviated as the robot is subjected to different conditions and forces such as its own weight, the pull and weight of its electric cord, underwater currents, different friction forces due to uneven surface elevation or texture, dirt on floor, asymmetrically (or even amorphically) shaped pools etc. Consequently all navigational algorithms of pool cleaning robots depend on numerous and even repeated cycles of sweeping in order to achieve substantial coverage of the pool.
When irregularly-shaped pools are considered, some sweeping algorithms appear to be inadequate and fail to substantially cover the pool""s floor.
It is the purpose of the present invention to provide a novel and improved method for navigating a pool cleaning robot on the bottom and side walls of a pool and an apparatus thereof.
Yet another purpose of the present invention to provide a method and an apparatus for navigating a pool cleaning robot that allow efficient and fast cleaning of the bottom and side walls of a pool.
Still another aim of the present invention is to provide such method and apparatus that allow high performance and coverage in cleaning irregularly shaped pools.
Other advantages and aspects of the present invention will become apparent after reading the present specification and viewing the accompanying drawings.
It is therefore thus provided, in accordance with a preferred embodiment of the present invention, a method for sweeping the floor of a pool by a pool cleaning robot initially set at an arbitrary position on the floor of the pool, the method comprising:
advancing the robot to until it encounters a wall;
reversing the robot and advancing it away from the wall, allowing the robot to travel a leg of predetermined distance;
turning the robot sideways in a predetermined angle of turn;
repeating the above steps until a predetermined number of wall encounters was counted, after which the predetermined distance of the leg is altered; and
repeating the above steps whereby a substantial area of the floor is covered by the robot.
Furthermore, in accordance with another preferred embodiment of the present invention, the predetermined angle of turn varies in some turns during the sweeping of the floor.
Furthermore, in accordance with another preferred embodiment of the present invention, the robot is initially positioned near a side end of the wall.
Furthermore, in accordance with another preferred embodiment of the present invention, the robot is initially positioned within a distance of 1 to 3 times the width of the robot from the side end of the wall.
Furthermore, in accordance with another preferred embodiment of the present invention, the angle of turn is substantially a right angle turn.
Furthermore, in accordance with another preferred embodiment of the present invention, the robot is turned in an angle of turn positioning the robot in a perpendicular direction to a facing wall.
Furthermore, in accordance with another preferred embodiment of the present invention, the alteration of the predetermined distance of the leg consists of increasing the length.
Furthermore, in accordance with another preferred embodiment of the present invention, the length of the leg is increased up to about half the length of the pool.
Furthermore, in accordance with another preferred embodiment of the present invention, the alteration of the predetermined distance of the leg consists of decreasing the length.
Furthermore, in accordance with another preferred embodiment of the present invention, the initial position of the robot at the commencing of the sweeping of the pool is about half way across the wall.
Furthermore, in accordance with another preferred embodiment of the present invention, the turn is taken constantly to the right with respect to the traveling robot.
Furthermore, in accordance with another preferred embodiment of the present invention, the turn is taken constantly to the left with respect to the traveling robot.
Furthermore, in accordance with another preferred embodiment of the present invention, the predetermined number of wall encounters counted prior to alteration of the length of the leg is 7.
Furthermore, in accordance with another preferred embodiment of the present invention, the alteration of the length of the leg is done in steps of constant lengths.
Furthermore, in accordance with another preferred embodiment of the present invention, the robot is a single motor driven robot having a powered horizontal impeller, and wherein the robot is turned by applying at least one of a plurality of predetermined number of interrupts in the impeller power thus causing the robot to acquire bias momentum directed sideways and hence move in the direction of the bias.
Furthermore, in accordance with another preferred embodiment of the present invention, the predetermined number of interrupts is between 15 to 25.
Furthermore, in accordance with another preferred embodiment of the present invention, the duration of the series of predetermined number of interrupts is in the range of about 10 to 20 seconds.
Furthermore, in accordance with another preferred embodiment of the present invention, each interrupt lasts about 0.5 to 0.8 seconds.
Furthermore, in accordance with another preferred embodiment of the present invention, there is provided a method for turning sideways a pool cleaning robot having a single motor drive and a powered horizontal impeller, the method comprising applying at least one of a plurality of predetermined number of interrupts in the impeller power thus causing the robot to acquire bias momentum directed sideways and hence move in the direction of the bias.
Furthermore, in accordance with another preferred embodiment of the present invention, there is provided a pool cleaning robot comprising:
a reversible motorized drive;
an impeller driven by a pump motor;
a power supply;
a processor for counting wall encounters and including a programmed algorithm for navigating and operating, the algorithm comprising the following steps:
advancing the robot to until it encounters a wall;
reversing the robot and advancing it away from the wall, allowing the robot to travel a leg of predetermined distance;
turning the robot sideways in a predetermined angle of turn;
repeating the above steps until a predetermined number of wall encounters was counted, after which the predetermined distance of the leg is altered; and
repeating the above steps whereby substantial area of the floor is covered by the robot;
a controller for receiving commands from the processor and reversing the robot and initiating turning of the robot upon the appropriate commands from the processor; and
a wall encounter sensor for sensing a wall encounter and sending a signal to the processor.
Furthermore, in accordance with another preferred embodiment of the present invention, the wall encounter sensor comprises a proximity sensor or a collision sensor or a tilt sensor or a sonar sensor.
Furthermore, in accordance with another preferred embodiment of the present invention, the reversible motorized drive is a reversible motorized caterpillar drive.
Furthermore, in accordance with another preferred embodiment of the present invention, the robot further comprises a GPS receiver for determining its position and direction.
Furthermore, in accordance with another preferred embodiment of the present invention, there is provided a pool cleaning robot comprising:
a reversible motorized drive;
an impeller driven by a pump motor;
power supply;
processor having a programmed algorithm for navigating and operating the robot, the algorithm includes inter alia applying at least one of a plurality of predetermined number of interrupts in the impeller power thus causing the robot to acquire bias momentum directed sideways and hence move in the direction of the bias;
controller for receiving commands from the processor and reversing the robot and initiating turning of the robot upon the appropriate commands from the processor.